And he has now taken an opportunity to express his anger at CSKA after they protested their innocence.

"I am not deaf," he said. "We are all humans. It is not a nice feeling to go and play a football match, to bring joy to the people and to be called a monkey or to hear monkey noises.

"I don't look like a monkey. Other people must have seen it.

"Doumbia is a young brother. Someone I admire who I have known a long time -- we come from the same country.

"I don't want to say things that will put him in trouble but you can see a little bit the manipulation around all this.

"It is so pathetic and so sad to see things like that. I am ashamed to still have to talk about this subject."

Should CSKA be found guilty the consequences could be far reaching.

They would almost certainly be forced to play at least one -- and possibly more -- matches behind closed doors, in addition to a potentially large fine.

There are also implications for Russia, with Ivory Coast international Toure warning on Friday that black players may consider boycotting the 2018 World Cup in Russia unless the issue is addressed properly.

However, he played down those comments, adding: "We know there are very large stakes for the country [Russia] around the World Cup.

"But let's leave FIFA and UEFA to do their work. UEFA has decided to apply the rules -- that's all we want.

"A lot of things have been said about racism. If today an organisation and supporters stray from the straight path or slip up, the goal is to see them straight again."